Pour depressant and sludge dispersant for middle distillates



3,235,347 POUR DEPRESSANT AND SLEDGE DISPERSANT FOR MEDDLE DISTILLATES William C. Hoiiyday, Jiu, Watchung, NJ, assignor to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Filed Earn. 4, 1962, Ser. No. 164,390 3 Claims. (Cl. 44-62) The present invention is concerned with improving the flow of fuels at low temperatures, improving pour point characteristics in middle distillates and also improving the sludge dispersing property. More particularly the invention relates to the preparation of improved low cold test hydrocarbon fuels, in particular heating oils and diesel fuels, kerosene, aviation turbo-jet fuels, and other fuels that are subject to low temperatures. A very desirable additive of the present invention comprises utilizing condensed chlorinated wax and phenol in a reaction with N-vinyl pyrrolidone.

With the increase in the use of hydrocarbon fuels of all kinds, a serious problem has arisen in areas frequently subject to low temperatures in the cold test characteristics of fuels. Particularly, serious problems have been encountered by heating oils and diesel and jet fuels that have too high a pour point, resulting either in distributional or operating difficulties or both. For example, the distribution of heating oils by pumping or syphoning is rendered difiicult or impossible at temperatures around or below the pour point of the oil. Furthermore, the flow of the oil at such temperatures through the filters cannot be maintained, leading to the failure of the equipment to operate.

It is, of course well known to add pour depressants to lubricating oils to lower the pour point. These lube oil additives, mostly high molecular weight organic compositions formed by alkylation of benzene or naphthalene or derivatives thereof or by polymerization of lower molecular weight methacrylates, or by condensation polymerization of various kinds, are not satisfactory in service with middle distillate and lighter fuels. Poor performance of these additives might possibly result from the structural difierences between waxes occurring in lubricating oils and so-called middle distillates.

A wide variety of compounds have been found to be effective as pour point depressants for lubricating oil. Among the best known are Paraflow, Santopour, and Acryloid and their modifications. They are prepared either by condensing aromatic compounds with long chain paratfins, such as wax, or by condensing olefinic esters. It is generally considered that these pour depressants are effective in that in cooling an additive-containing oil, the hydrocarbon chain of the additive becomes incorporated into the crystal lattice of the separated wax, while the other part of the pour depressant molecule prevents the crystals from adhering together to form a gel structure. The failure of these additives to be effective in middle distillates may at least in part be due to the 7 basic difierence in the composition between the wax in lubricating oils and that in middle distillate fuels.

It is, therefore, the principal object of the present invention to set forth an improved pour depressant for middle distillate and lighter fuels. The boiling ranges of these oils are generally about 250 to 750 F.

The petroleum distillate fuels in which the additive materials of the invention are employed consist of a major proportion, at least 95 of liquid hydrocarbons boiling at temperatures between about 70F. and about 750 F. These fuels include gasolines such as aviation, marine and automotive or motor gasolines, aviation turbo-jet fuels such as JP1, JP-4 and IP-S fuels, and diesel fuels itd Stats Patent such as marine, stationary and automotive diesel engine fuels.

Aviation turbo-jet fuel consists of at least of a mixture of volatile hydrocarbons. It is defined by U.S. Military Specifications MILF5616 and MILF5624C. Its volatility is such that its end point does not exceed 572 F. Its viscosity is between 0.5 and 1.5 centistokes at F.

Diesel fuels as referred to in connection with the invention consist of at least 95% of a mixture of hydrocarbons boiling between 250 F. and 750 F. either by ASTM Method D86-56 when their end points do not exceed 600 F; or by ASTM Method Dl5854. Diesel fuels are defined by ASTM Specification D975-53T and fall into grades 1D, 2D and 4D, in all of which the additive materials of the invention may be used. They have viscosities between 1.4 and 26.4 centistokes,

The liquid fuels in which the additive materials may be incorporated thus comprise at least 95 by weight of a mixture of hydrocarbons having a boiling range between the limits of 75 F. and 750 F. and a viscosity between the limits of 0.264 and 26.4 centistokes at 100 F.

Thus, the present invention is concerned with the use of a material which is secured by chlorinating waxes of particular chain length and thereafter reacting these chlorinated waxes with a phenol and then further reacting with N-vinyl pyrrolidone.

In the preparation of the multi-purpose additive of the present invention, the normal parafiin should have from about 19 to 25 carbon atoms in the chain and should preferably average about 21 to 23 carbon atoms in the chain. A preferred parafiin, if no range is utilized, is one having about 22 carbon atoms in the molecule.

This parafiin or mixture of paralfins having the desired number of carbon atoms in the chain is then chlorinated so as to secure a chlorinated product having 18 to 30% of chlorine present therein by weight, preferably from about '20 to 26% by weight of chlorine in the product.

The chlorinated product is then condensed with phenol in a manner to produce a phenol condensation product having 10 to 25% by weight of phenol present, preferably about 12 to 20% by weight of phenol present in the chlorinated paraffin.

A multi-purpose additive is secured by reacting the paraffin-chlorine-phenol condensation product with N- vinyl pyrrolidone. Suificient N-vinyl pyrrolidone is utilized so as to secure 1 to 10% by weight of N-vinyl pyrrolidone present in the product, preferably from 2 to 5% by weight of N-vinyl pyrrolidone present in the product.

EXAMPLE 1 Eicosane (chemically pure n-C H was chlorinated to 26.0% chlorine by passing chlorine gas into the melted hydrocarbon at about 95 to C.

A mixture of 100 g. of this chlorinated eicosane and 16.3 g. of phenol was treated with 3 g. of anhydrous aluminum chloride at 70 C. The temperature was gradually raised to C. over 2.5 hours. At the end of this time the product was cooled, diluted with hexane and washed with hydrochloric acid and saturated sodium bicarbonate solutions. Volatiles were evaporated on the steam bath and 90.7 g. of non-volatile product were obtained. The product contained about 17.7% of phenol by weight. This product was an excellent pour depressant for middle distillates as shown in the following Table I.

EXAMPLE 2 A mixture of 39.5 g. of alkylated phenol from Example 1, 5.0 g. of N-vinyl pyrrolidone and 0.2 g. of sulfur was heated at 150 C. for one hour. The temperature was then raised to C. momentarily. The mixture was cooled and diluted with hexane. The hexane solution was thoroughly washed with water to remove unreacted N- vinyl pyrrolidone and N-vinyl pyrrolidone polymer and then the hexane was removed on the steam bath. Yield of product 41.0 g., containing 0.38% nitrogen, equivalent to 3.0% N-vinyl pyrrolidone in the polymer. The excellent pour depressant properties are shown in Table I.

Table I Base stock plus Product produced by wt. percent polymer Example 1 Example 2 The base stock is a heating oil from mixed straight run and catalytically cracked stocks with a cloud point of about +8 F., a pour point of about F., and a boiling range of about 346 to 628 F.

The sludge dispersing properties of the above are shown in the following Table II.

1 Formed during storage at 200 F. for 16 hours.

Other tests were conducted as illustrated by the following examples.

EXAMPLE 3 A commercial, highly n-parafiinic wax with a melting point of 43 C., an average molecular weight of 313 averaging about n-C H in composition and ranging from about C H to C H was chlorinated to 20.5% chlorine.

To a mixture of g. of phenol and g. of this chlorinated wax was added at 50 C. 10 g. of anhydrous aluminum chloride and this mixture was stirred at 50 C. for one hour. At the end of this time the temperature was raised to C. and over one hour 190 g. additional chlorinated wax was added. The temperature was then raised and maintained at C. for 5 hours.

After working up the product as described in Example 1, the total yield was 224.3 g. When this material was extracted with warm methanol the yield of methanol insoluble product was 215.2 g., which contained 1.17% chlorine. The product was soluble in all hydrocarbons and an excellent pour depressant for middle distillate fuels as shown in Table III.

Table III Base stock plus wt. Product produced percent polymer: by Example 3 EXAMPLE 4 A mixture of 50.0 g. of the alkylated phenol from Example 3, 10.0 g. of N-vinyl pyrrolidone and 0.5 g. of sulfur was heated at 140 to C. for 3 hours. After working up the product as described in Example 2, there was obtained 50.1 g. of product containing 0.29% nitrogen equivalent to 2.3% N-vinyl pyrrolidone. The sludge dispersant properties of the product is shown in the following Table 1V.

1 Formed during storage at 200 F. [or 10 hours.

Additional tests were conducted as described with respect to Examples 1 to 4 inclusive. The relative quantities of the reactants used and other pertinent data with respect to Examples 5 to 10 are set forth in the following Tables A, B, and C.

With respect to Example 9, the reaction mixture contained 100.5 g. of chlorinated wax (20.7% chlorine from wax melting at 42 C.) 16.9 g. of l-naphthol and 3.5 g. of anhydrous aluminum chloride. The yield of product was 103.0 g.

As to Example 10, without separating the Chlorowax/ naphthol condensate from the aluminum chloride catalyst, half the reaction mixture was treated with 10 g. N-vinyl pyrrolidone, and this then was heated at C. for half an hour. The product was worked up as in Example 2 and contained 0.29% nitrogen.

Table A PREPARATION OF CHLORINATED WAXES Distillation Percent Example n-Parailln M01. wt. of range of Wax, chlorine in number chlorinated paraffin 1U chlorinated wax 313 356 to 478-... 20. 5 313 350 to 478.... 23. 5 320 356 to 485.... 20.7

1 Vacuum distillation at 10 mm. Hg.

Table B PREPARATION OF ALKYLATED HYD ROXY-AROMATICS Hydroxy- Chlorinated Example aromatic wax Ratio: Product, number Cl./arorn. g.

Type G. Percent G.

5 Phenol.-.. 10. 0 20. 5 80. 5 .36 73.7 7.-- .-..-do...-. 15.0 23. 5 80.0 5.32 76.1 9.-. l-naph- 16.0 20.7 100.5 4. 98 103.0

thol

Table C PREPARATION OF N-VINYL PYRROLIDONE DERIVATIVES OF ALKYLATED PHENOLS Alkyl phenol Example Product, g. Percent N number in product Ex. No. G.

1 Calculated from gain in weight. 1 By analysis.

The pour depressant properties of the products produced by the technique of Examples 5 to 10 inclusive are shown in the following table.

It is preferred that the molecular weight of the product be in the range from 1200 to 8000, preferably in the range from 1800 to 4000. It is also preferred that from 0.001 to 0.500% of the material be used, preferably from 0.005 to 0.050% of the additives. A preferred molecular Weight is about 2500 while a preferred concentration is in the range from about .02 to .03 wt. percent.

The relative sludge dispersant properties of the products from Examples 3 and 4 were further demonstrated by the following tests. Sludge was obtained from an oil which had been drained from an automobile by diluting the used oil with hexane and centrifuging. A given amount of this sludge was added to various oil blends as described below, to test the ability of each of these blends to hold the redispersed sludge in suspension. The base stock for each of the blends was a light colored SAElO base stock (ASTM color of 1). The reference blend contained only the standard amount of redispersed sludge and no additive. persed sludge, 0.5 wt. percent of the polymer from Example 3, while another blend contained sludge and 0.5 Wt. percent polymer from Example 4. The blends were centrifuged to reprecipitate the sludge if possible. Precipitation of sludge was measured by color changes, which will be made clear by examining the following table.

Table VI SLUDGE SUSPENSION TESTS One test blend contained in addition to the redis- ASTM color and appearance Blend tested Original blend After centrifuging Base stock: No sludge, 1-Clear 1Olear.

no additive. Base stock plus sludge, 4Hazy 2V. sl. haze.

no additive. Base stock plus sludge 4-Hazy 3V. sl. haze.

plus 0.5 wt. percent polymer Ex. 3. Base stock plus sludge 4-Hazy 4-V. sl. haze.

plus 0.5 wt. percent polymer Ex. 4.

The ASTM color scale is such that each higher number in the scale indicates roughly a doubling in the concentration of color bodies present. In the case of the blends described in Table VI, the finely divided sludge constitutes the color bodies, while the coarser sludge particles, which can be removed by filtration, constitute the haze. It will be noted that the product from Example 4 holds in suspension all of the finest sludge. The product from Example 3 is also an eifective sludge dispersant, al though it holds only half the sludge in suspension compared to the product from Example 4. The fresh oil with no additive is capable of suspending only a fourth as much sludge as the product from Example 4.

The dispersant action exhibited by Examples 3 and 4 helps to maintain cleanliness and reduce wear in oil burners and in engines by keeping dirt particles in suspension until the fluid passes through or is drained from the equipment, instead of allowing these particles to precipitate in regions of close clearance where plugging and Wear may occur. Experience has shown that this dispersant action also has an inhibiting effect on sludge formation, as well as a dispersant eifect once the sludge has formed.

What is claimed is:

1. A petroleum distillate fuel composition consisting essentially of a petroleum distillate fuel having a boiling range between about 250 and about 750 F. containing a pour point depressing amount, within the range of about 0.001 to 0.5 wt. percent, of an oil-soluble copolymer having a molecular weight of about 1200 to 8000 consisting essentially of N-vinyl pyrrolidone and alkylated phenol, said alkylated phenol having C to C alkyl groups and containing about 10 to 25 wt. percent phenol, and said copolymer containing about 1 to 10 wt. percent of said pyrrolidone monomer.

2. Composition as defined by claim 1 wherein the alkyl chain is from about 21 to about 23 carbon atoms and wherein said product contains from about 12 to 20% by weight of phenol and wherein said product has a molecular weight in the range from about 1800 to 4000.

3. Composition as defined by claim 1 wherein the alkyl chain contains about 22 carbon atoms wherein the weight percent of phenol present in the product is about 16% and wherein the molecular weight is about 2500, said composition also containing from about .0" 0 about .03% by weight of said product.

References Cited by the Examiner UNITED STATES PATENTS 2,125,875 8/1938 Barnard 44-78 X 2,213,596 9/1940 Shmidl 44-78 2,348,638 5/ 1944 Mikeska 44-62 2,489,000 11/1949 Valentine 252-403 2,721,176 10/1955 Cantrell 44-62 X 2,831,898 4/1958 Ecke et al 44-78 2,984,553 5/1961 Andress 44-78 FOREIGN PATENTS 808,665 2/ 1957 Great Britain.

' DANIEL E. WYMAN, Primary Examiner.

JOSEPH R. LIBERMAN, Examiner. 

1. A PETROLEUM DISTILLATE FUEL COMPOSITION CONSISTING ESSENTIALLY OF A PETROLEUM DISTILLATE FUEL HAVING A BOILING RANGE BETWEEN ABOUT 250* AND ABOUT 750*F. CONTAINING A POUR POINT DEPRESSING AMOUNT, WITHIN THE RNGE OF ABOUT 0.001 TO 0.5 WT. PERCENT, OF AN OIL-SOLUBLE COPOLYMER HAVING A MOLECULAR WEIGHT OF ABOUT 1200 TO 8000 CONSISTING ESSENTIALLY OF N-VINYL PYRROLIDONE AND ALKYLATED PHENOL, SAID ALKYLATED PHENOL HAVING C19 TO C25 ALKYL GROUPS AND CONTAINING ABOUT 10 TO 25 WT. PERCENT PHENOL, AND SAID COPOLYMER CONTAINING ABOUT 1 TO 10 WT. PERCENT OF SAID PYRROLIDONE MONOMER. 